This is a U.S. Couterpart of German Patent Application DE 199 61 748.1, with a foreign filing date of Nov. 19, 1999, the disclosure of which is incorporated into this application by reference.
The invention relates to an analytical balance having a balance housing, which includes a base area and a back structure, and a balance scale. The analytical balance further includes a wind guard that encircles the balance scale and that has a base surface formed by the base area of the balance housing and a back wall formed by the back structure of the balance housing. The analytical balance further includes a fixed front pane, two movable side panes, and a movable upper sliding door. Moreover, the movable wall elements can be opened and closed by hand or by motor.
Balances of this type are generally known and are described in U.S. Pat. No. 4,664,207 (corresponding to Laid Open German Application DE 35 08 873 C1) or U.S. Pat. No. 4,700,793 (corresponding to EP 234 008 B1), for example.
In U.S. Pat. No. 4,664,207, a frameless front pane is fastened to a base area of a balance housing and, in addition, is held at its upper end by two guide rails. The frameless front pane is connected to a back structure of the balance housing. The two guide rails serve simultaneously as guides for the upper sliding door and for the side panes. This provides a very simple configuration for guiding an upper sliding door, as well as providing stability for the front pane. Furthermore, the view of the goods being weighed is essentially unobstructed from both the front and the sides, and the fixed guide rails only obstruct the view and access from obliquely above.
In U.S. Pat. No. 4,700,793, the accessibility and the view from obliquely above are unobstructed because the guide parts that connect the sliding side panes to the upper sliding door are slidable into or over the back structure of the balance housing. However, this configuration is quite complicated. Furthermore, the displacement of the guide parts results in the incomplete guiding of the side panes at the back of the analytical balance over their entire area, when the upper sliding door is open. In contrast, the side panes are guided along their entire length when the upper sliding doors are closed.
Conversely, if both sliding side panes are open, the guide parts of the upper sliding door lack support. Thus, this arrangement suffers from the problem that the guide parts sink forward somewhat, due to insufficient rigidity, and the side doors are difficult to access. Also, the upper sliding door is relatively difficult to access because both the friction of the entrained guide parts and the friction between the guide parts and the side panes must be overcome. Furthermore, in U.S. Pat. No. 4,700,793, the lateral view from the front is obstructed by an encircling frame around the front pane.
According to one objective of the present invention, it is sought to combine the advantages of the two specified types of construction, while avoiding the disadvantages thereof. In particular, the side panes and the upper sliding door should be moveable without affecting one another. In addition, the view of the goods being weighed should be unobstructed from the front and the side, as well as from above and obliquely above. Moreover, access to the goods to be weighed, both from above and from the sides, should also be unobstructed.
These and other objectives are achieved by providing an analytical balance including a balance housing having a base area and a back structure, a balance scale, and a wind guard encircling the balance scale. The wind guard includes a base surface formed by the base area and a back wall formed by the back structure. The wind guard further includes a fixed front pane, a right and a left movable side pane, and a movable upper sliding door.
The fixed front pane is implemented without a frame and is fastened to the base area of the balance housing. Preferably, the front pane is fastened only on the base area. The right and left side panes are guided on the base area and are secured on the back structure. Preferably, the side panes are secured at the back structure only against tilting. The upper sliding door is guided by at least one sliding guide on the back structure of the balance housing.